PURPOSE: To eliminate the influence caused by the reflection on the incidence surface of the photo isolator by making the optical axis of the semiconductor laser diode inclined to the optical axis of the photo isolator.
CONSTITUTION: The emitted light from the laser diode 11 comes incident to an optical fiber 18 via photo isolator 12. The isolator 12 consists of a parallel light converting lens 13, a polarizer 14, a Faraday rotor 15, a photodetector 16, and a converging lens 17. The incidence surface of the lens 13 is at a right angle to the optical axis of the isolator 12. The optical axis of the emitted light of the diode 11 is arranged by inclination to the optical axis of the isolator 12. Therefore, the reflected light on the incidence surface of the lens 13 does not follow the same path as at the time of incidence of light.
IIYAMA KEIICHI
TOUJIYOU MASAAKI
MOCHIDA YOSHIHISA
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